Here is my problem. Today my car started to hesitate,ESS light came on and code 42 pop up. This is what code 42 says (Fault at electronic spark timing circuit or Fault at direct ignition system or Fault at fuel cutoff relay circuit). What do i check first.
OK i have new dis,wires,cap,rotor,and fuel filter
PLease Help

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• 1987 T/A 350tpi, 5speed, Stock exhaust, Gutted Cat,Compucam 2030 429 452 & 204 214,TbBypass,Ported Plenum,AFPR. 14.37@93.4mph 1.99 60ft

[This message has been edited by Larrys T/A (edited July 24, 2000).]

 

ttt

 

I know there are some Master Mechanics out there.

 

Larry, verify the EST bypass connector is not loose...look at the emissions label, believe it says a "single wire connector tan/blk wire code", mines located behind the pass. side strut tower, FWIW.

 

Must be something in the air! Mine started doing the same thing last Friday idels fine but under load it misses Pulled the ing mod and had it tested and it's fine. Talked to a GM tech he said it could be a bad plug or wire... Got them so I will do them tomorrow... Let ya know... Also search the old posts thats what I did...

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85 T/A 5.0 H.O.WS6 TPI Auto
Bone Stock! For now...

 

Thanks guys for the reply. What i did was reset the computer, and so far no problem yet. I also reset my IAC sensor.

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• 1987 T/A 350tpi, 5speed, Stock exhaust, Gutted Cat,Compucam 2030 429 452 & 204 214,TbBypass,Ported Plenum,AFPR. 14.37@93.4mph 1.99 60ft

 

Hey Larry~ You said you reset your computer and all is well. 2 questions: 1. How did you do it? 2. Would you recommend it if there's really nothing wrong with the car? I'm just wondering if maybe it would run a little better if the computer were back to original specs or is the cpu constantly adjusting itself to make up for anything that might be off kilter. Anything anyone could share would be greatly appreciated. Thanks guys~~~~ witchdr666@aol.com

P.S. What is the IAC sensor?
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`85 Z28 5.0L TBI
Don't ever be:
Found On Road Dead!

[This message has been edited by witchdr (edited July 25, 2000).]

 

You can reset the ECM (computer) by either removing the negative battery cable for a few minutes or, if you don't want to reset your radio controls, pulling the ECM fuse that is right next to the battery, on my Trans Am it's on the driver's side mounted right next to the radiator. Looks like a small weatherpack connector, just pull it out and you'll see the fuse and pull that out for a few minutes.

As far as the IAC "sensor" it's not really a sensor per se, but it is most often referred to as a motor, as it controls the passage of air into the plenum while at idle with the throttle blades closed, thus the name IAC, for Idle Air Control. The procedure for setting the IAC is outlined here: https://www.thirdgen.org/tech/tpimod2.html
Don't forget to set your TPS voltage when you're done. Hope this helps.

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Kevin Irving
85 Trans Am WS-6, 305 TPI, custom burned '86 PROM with '87 "165"ECM, Accel Supercoil & 8.8 Wires, MSD 6AL, Aluminum Driveshaft, TB Coolant Bypass, Ported Plenum, Modified MAF, Cyclone Fuel Pump, JET Airfoil

Veiw my car at: http://www.geocities.com/transam85tpi/TransAm.html

 

I found a plug wire loose...Duh! replaced them all and new plugs... WOW what a pain in the ...Runs fine now...

 

Thanks Kevin for clearing that up for me. He is right its called a IAC (idle air control valve). As far as resetting the computer Witchdr, if your car is running ok don't fool with it. Hope I was some help to you.

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• 1987 T/A 350tpi, 5speed, Stock exhaust, Gutted Cat,Compucam 2030 429 452 & 204 214,TbBypass,Ported Plenum,AFPR. 14.37@93.4mph 1.99 60ft

 

Yeah guys, thanks! s'funny though, I was having ignition system problems not too long ago (the culprit ended up being a half-*** alarm install), and so I had the battery cable on and off 20 times a day as I was trying different things to get it fired up again. Gee, I guess it's as reset as it'll get. Later~~

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`85 Z28 5.0L TBI
Don't ever be:
Found On Road Dead!

 

Vader helped me with a code 42 not too long ago. There is a 'chip' inside your underneath the rotor in the distributor. This is the Electronic Spark Control Module. Mine was a thermal prob where after my car got warm, the chip would heat up and cut off. In the 83' models, the computer kills the engine after receiving ( or not receiving ) a signal from this module. Replace it. Only $25 at AutoZone. Mine was an INTERMITTENT problem and took me a while to figure out what the *** was going on with my car. Good luck.

Late -

D